1. Field of the Invention
The present invention relates to a seat with a user restraint. More particularly, the present invention relates to a seat with a user restraint which has a sitting portion and a user restraining system.
2. Description of the Prior Art
Seats with a user restraint of the above mentioned general type are known in the art. One such seat with a user restraint is disclosed, for example, in a seat with an integral two point user restraint, shown in FIG. 1. The existing two point, or lap belt only, restraint system, however, has one main disadvantage. It does not offer maximum protection to the user during frontal or side impacts. A user who is belted only at the hips can rotate the torso forward or sideways during an impact. This would allow the user to strike the steering wheel or other vehicle components.
Another such seat with a user restraint is disclosed, for example, in a seat with a three point user restraint. A conventional three point, or lap and shoulder belt system, consists of attaching the retractor to part of the vehicle structure beside or below the seat and passing the belt through a "D" loop mounted on the vehicle structure above and behind the user's shoulder. The end of the belt being fixed to a point near the retractor. A tongue which is free to slide is located on the belt between the fixed end and the "D" loop. When the tongue is drawn across the body of the user and latched into the buckle, the seat belt lays across the hips as well as the chest of the user. However, during an impact the belt will stretch and undergo spool down. Spool down is a tightening of the belt on the spool as the end of the belt is pulled. The spool itself is locked and will not turn, but the belt will play out of the retractor as the belt tightens on the spool. These two phenomena increase as belt length increases. The longer the belt, the more belt is stored on the spool. Belt stretch is a percentage of the belt used, so that the longer a belt is the longer it will stretch. If the shoulder belt spools out before it can retain the user then no advantage is gained by using it. The user's torso would still travel far enough to strike vehicle components. To be most effective a three point user restraint system requires minimal belt length. Since a walk-in van requires extreme belt lengths because the anchorages are on the vehicle structure, the variety of body sizes as well as driver locations which vary with chassis, would require a different three point user restraint system for each type of application.